You would think AirBnB would get more involved in pricing (like Uber). Perhaps, though, it considers stable prices more community-friendly?
Generally speaking that's a poor time to be flooding the market with inexperienced, new hosts and the requisite spike in bad customer experiences.
Hospitality differs substantially from Uber in the sense that quality of service is extremely important in a way it isn't on Uber (or at least, UberX).
I suspect they think it might be community-unfriendly and/or complicate the service.